Low-energy exchange reactions between hydrogen isotope mesoatoms

In terms of the Faddeev-Hahn equations in the two-level approximation the exchange reactions in low-energy hydrogen isotope mesoatom collisions for the total momentumL=0 have been considered. Elastic and inelastic cross-sections of the scattering channels as well as the rates of the exchange reactions for the (d+p) and (t+p) collisions have been calculated.     

Quadrupole moment and quadrupole relaxation of spin of muonium and mesoatoms

It is shown that muonium in the ground state has a quadrupole moment. Existence of the quadrupole moment of muonium leads to essential influence of crystal electric fields on the precession and relaxation of its spin in a medium.     

Model for milling of powders

A model is proposed for mechanical milling of powders that relates the applied energy to average particle size D in the powders. It is shown that the milling energy is consumed for the rupture of interatomic bonds in crystalline particles and for the creation of an additional surface during powder fragmentation. The appearance of microstrains ɛ retards powder fragmentation. Average particle size D after milling decreases with increasing milling time t and decreasing particle size in the initial powder or its mass M. The calculated results are compared to the experimental data obtained on a tungsten carbide WC powder.     

A Model for Polyelectrolytes

We have solved a polymerizing version of the mean spherical approximation (MSA) for polyelectrolytes. The polyelectrolytes are modeled as tangentially bonded hard-sphere segments interacting via the Coulombic potential in a continuous medium with dielectric constant. Analytical solutions for thermodynamic properties and radial distribution functions at contact are obtained for some specific systems (negatively charged chains and counterions) studied in the literature via computer simulations, with which good agreement is found for the osmotic pressure.     

Model for Topological Fermions

 We introduce a model designed to describe charged particles as stable topological solitons of a field with values on the internal space S ³. These solitons behave like particles with relativistic properties like Lorentz contraction and velocity dependence of mass. This mass is defined by the energy of the soliton. In this sense this model is a generalization of the Sine-Gordon model¹(We do not chase the aim to give a four-dimensional generalization of Coleman’s isomorphism between the Sine-Gordon model and the Thirring model which was shown in 2-dimensional space-time) from 1 + 1-dimensions to 3 + 1-dimensions, from S ¹ to S ³. For large distances from the centre of solitons this model tends to a dual U(1)-theory with freely propagating electromagnetic waves. Already at the classical level it describes important effects, which usually have to be explained by quantum field theory, like particle-antiparticle annihilation and the running of the coupling. Received November 30, 1999; revised June 20, 2000; accepted for publication October 2, 2000     

A Model for Neutrinos

Neutrinos are the weirdest of elementary particles, nearly massless and chiral. They oscillate between flavours, furthermore. We try to find a rationale for this maverick behaviour.     

Model for Thermal Oxidation of Silicon

Technical Physics - Nanometer-thick silicon oxide films are needed for miniaturization and increase in the working rate of electronic devices. Interpretation of the initial stages of silicon...     

Model for ion-initiated trench etching

We model the plasma etching of trenches by Langmuir kinetics for neutral molecules and bombarding ions. The parallel combination of an isotropic etch rate for the neutrals and an anisotropic etch rate for the ions gives an effective etch rate. The ion etch rate is proportional to the normal surface component of the ion energy flux. An approximate analytical expression for the composite etch rate offers a new approach to the computation of etch profiles for these mixed systems. Etch profiles are displayed for three cases: the nearly ion flux-limited regime, an intermediate case, and the nearly neutral-flux limited regime for the trench bottom. The numerical calculation of the etch profiles follows from the integration of three characteristic strip equations which are nonlinear first-order ordinary differential equations (ODE's)     

A Markov Model for Kinesin

We investigate the validity of a Markov approach for the motility of kinesin. We show in detail how the various mechanochemical states and reaction rates that are experimentally measured, can be used to create a Markov-chain model. We compare the performance of this model to motility data and we find global similarities in the load and ATP-concentration dependency of speed and mean run length. We also discuss the relation between the experimentally found stalling behavior and thermodynamic expectations. Finally, the Markov chain modelling provides a way to calculate the mean entropy production and the (power) efficiency.     

Model for reversible colloidal gelation

We report a numerical study, covering a wide range of packing fraction Phi and temperature T, for a system of particles interacting via a square well potential supplemented by an additional constraint on the maximum number n(max) of bonded interactions. We show that, when n(max)<6, the liquid-gas coexistence region shrinks, giving access to regions of low Phi where dynamics can be followed down to low T without an intervening phase separation. We characterize these arrested states at low densities (gel states) in terms of structure and dynamical slowing down, pointing out features which are very different from the standard glassy states observed at high Phi values.     

Relativistic Fermi-Gas Model for Nucleus

Spin-half fermions are considered to be limited in a spherical potential well with periodic boundary conditions. The whole system is treated like a relativistic Fermi Gas. Solving the corresponding Dirac equation, the density of states, the Fermi energy, the average energy, the density of states of nucleons and the total energy of the ground-state are obtained.     

基于多Agent的飞机电子仪表系统仿真模型

电子仪表系统（EIS）在飞机飞行和维护过程中对飞机性能参数的显示具有至关重要的作用。针对电子仪表系统（EIS）功能仿真提出一种基于多Agent的电子仪表系统建模方案,从整体角度对系统功能进行了描述和分类,在功能分类的基础上建立了层次化系统结构模型,利用混合型Agent对系统功能对象的结构进行了设计并建立了系统功能行为模型。最后以发动机N1转速超限为例对上ECAM显示功能进行验证,证明该方法在飞机电子仪表系统仿真建模的实用性和可靠性。     

An Improved Pinchoff Equivalent Circuit Model for Determining PHEMT Model Parameters for Millimeterwave Application

An improved equivalent circuit model under pinchoff condition for extracting parasitic model parameters for Double Heterojunction -doped PHEMTs is presented. Good prediction for S parameters and noise performance are obtained up to 40GHz. A modified parameter extraction technique based on this new model was use to determine a PHEMT equivalent circuit model. Signification improvements of the accuracy of S parameters are obtained by using the new pinchoff model.     

Interest-Driven Model for Human Dynamics

Empirical observations indicate that the interevent time distribution of human actions exhibits heavy-tailed features. The queuing model based on task priorities is to some extent successful in explaining the origin of such heavy tails, however, it cannot explain all the temporal statistics of human behavior especially for the daily entertainments. We propose an interest-driven model, which can reproduce the power-law distribution of interevent time. The exponent can be analytically obtained and is in good accordance with the simulations. This model well explains the observed relationship between activities and power-law exponents, as reported recently for web-based behavior and the instant message communications.     

Geometrical Model for Phenylthallium Dihalides

The geometry of the phenylthallium dihalides, PhTlX₂(X=F, Cl or Br) which has heitherto been unknown, has been proposed on the basis of several qualitative aspects and quantitative arguments. These molecules have a planar structure with C_2v symmetry and the ring geometry has been assumed to be the same as that of benzene. The ring-substituent bond length has been taken to be 2.218 A° in all the three molecules, and the Tl-F, Tl-Cl and Tl-Br bond lengths in respective molecules have been estimated to be 1.878, 2.366 and 2.520 A°. The remaining parameter inter-bond angle, F-Tl-F has been taken to be 116° in PhTlF₂, whereas, angles Cl-Tl-Cl and Br-Tl-Br in respective molecules have been taken to be 120°, as expected in the case of a pure sp² hybridization.     

A Model for Branch Competition

Branching (or tip-splitting) is a ubiquitous feature of growth processes in nature. We introduce a simple model, linear in growth probabilities, of branch competition that combines tip-splitting processes, local screening, and extinction of branches whose growth has come to an end. This model admits an exact solution; which is corroborated by numerical results. An extension of the model that depends quadratically upon growth probabilities exhibits a phase transition, with non-trivial scaling in the neighborhood of that transition.     

Model for high-energy baryon-antibaryon annihilation

A model for annihilation is presented, based on a simple multiperipheral interpretation of the corresponding dual unitarity diagrams. The model exactly conserves internal quantum numbers and leads to characteristic correlations and leading particle effects associated with the topology of the dominant diagrams. Uncertainties about non-leading terms prevent a direct comparison with annihilation data at low energies, but a fit to high-energy data on $\text{p}\text{p}\text{-}\text{pp}$ cross-section differences, motivated by the similarities between the differences studied and genuine annihilation data where these can be compared, shows excellent agreement when the mesonic objects produced in the model are taken to be clusters of the same type as those produced in non-annihilation processes.